Electric discharge device



Jan 2% i925 mzmw A. W. HULL ELECTRIC DI SCHARGE DEVICE Original Filed May 21, 1920 7 Inventor Albert W. Hul I, by h 4 M His Attorneys Patented Jan. 20, 1925.

UNITED STATES PATENT OFFICE.

ALBERT W. HULL, F SCHENECTADY, NEW YORK, ASSIGNOB- T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC DISCHARGE DEVICL.

Application filed May 21, 1920, Serial No. 383,269. Renewed September 4, 1924.

v To all whom it may concern:

Be it known that l, ALBERT W. HULL, a citizen of the United States, residin at Schenectady, county of Schenectady, tate t of New York, have invented certain new and useful Improvements in Electric Discharge Devices, of which the following is a specification.

The present invention relates to the con- 1 trol and amplification of electric currents.

My invention comprises a novel method and apparatus whereby an electron current is subjected to the conjoint action of a variable electric field and a variable magnetic field. My invention also includes apparatus for utilizing my new method for the control of high frequency oscillations partic ularly for the sending of radio signals. The novel features of my invention will be point- 22 ed out with greater particularity in the appended claims. For a more complete understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawing in which Fig. 1 illustrates a telegraphic sending apparatus embodying my invention; Figs. 2 and 3 illustrate different forms of radio telephonic sending apparatus embodying my invention; and Fig. 4 illustrates in as somewhat greater detail structural features of a device embodying my invention.

In my prior application, Serial No. 354,914, filed January 29, 1920, l have described and claimed a method and means for as controlling an electron discharge by a varying magnetic field. The therein described electron discharge apparatus is provided with means for generating a magnetic field having such relation to the electrodes that an an increase of field strength above a value depending on the structure of'the device reduces the current-carrying capacity of the device. 1

My present invention comprises electron 4 devices having an electrostatic control n1e1nber, such as the well-known grid, in addition to means for subjecting the electron. current to a magnetic field.

Referring to the drawing, Fig. 4 illusim trates an embodiment of my invention comprising an elongated glass receptacle 7 containing an axially located filamentary cathode 8, connected to sealed-in conductors 9, 10. A spring 11 may be provided to hold the filament taut. Surrounding the filament is a spiral electrostatic control member 12 which hereinafter will be referred to as the grid. This grid 12 is attached, as by welding, to wires 13, 14: embedded in the stem 15. Outside of the grid 12 is a cylindrical anode 17 connected to a sealed-in conductor 18. A magnetic winding 19 is provided outside of the envelope 7.

The space within the container preferably is evacuated and the parts of the apparatus suflicientl'y denuded of gas to enable a substantially pure electron discharge to occur through the evacuated space between the cathode and the anode. An electron current between the electrodes 8 and 17 ma be variedby electric charges on the grid 12, a negative charge reducing the electron current and a positive charge increasing the electron current.

A magnetic field generated by the winding 19 substantially parallel to the cathode operates to vary the current-carrying capacity of the space between the cathode and the anode. In accordance with my invention, an electron current in the tube is controlled simultaneously by the electric and magnetic field.

Fig. 1 illustrates one useful embodiment of a combined electrostatic and electromagnetic control in a radio apparatus. The cathode 8 and the anode 17 are connected respectively by the conductors 21, 22 to the secondary of a transformer 23, the primary of which is connected in series with an antenna 24. lin circuit with the conductors 21', 22, is a suitable source of direct current, as, for example, a battery 25. The cathode 8 is maintained at incandescence by a suit able source of current, such as a battery 26. The grid 12 is coupled to the cathode S by a conductor 27 containing an inductance coil 28 and is coupled to the anode 1? by a con ductor 29 in series with an adjustable eondenser 30. The magnetic winding 19 is con nested by the conductors 31, 32 to a able source of current, as, for example, a battery 33.

By proper tuning of the capacity and the inductance, high frequency oscillations are produced in the output circuit 21, 22 by the variations of the electric charge of the grid 12 between negative and positive values. With a magnetizing current of proper value energizing the coil 19, the current-carrying capacity of the space between the cathode 8 and the anode 17 may be reduced at will or current flow cut off entirely. For example, radio signals may be sent by transmitting oscillations produced as above described to the antennae 24 by varying the strength of the magnetic field between a value sufficient to materially reduce electron current and a lesser value. In order to send telegraphic signals this may be done by opening the circuit 31 by a telegraph key 34 or any other suitable means. When the circuit 31 is open the magnetic field of the coil 19 no longer suppresses current flow.

The telephonic sending apparatus shown in Fig.2 istgrovided with an oscillating grid circuit containing an inductance coil 28 and a capacity connection 30 between the grid and the anode 17, 'as already described in connection with Fig. 1. The device of Fig. 2 is also provided with means for varying the current in the magnetic control coil .19 in accordance with the variations of an audio current to correspondingly modify 32 are connected to a source of direct current 38 in series with inductance coils 39, 40. A single inductance coil in some cases is sufficient. A polarizing current flows through this circuit to the coil 19, this polarizing current being of such value that a slight increase of current will produce a material decrease in the amplitude of the oscillations. A telephone circuit 41, containing a transmitter 42, a battery 43, and an inductance coil 44 is coupled to the conductors 31, 32 by the condensers 45, 46. Variations of current of audio frequency in the circuit 41 flow through the condensers (which preferably should be of large ca pacity), and are superimposed on the polarizing current in the coil 19. As a result the conductivity of the device 35 is varied in accordance with the variations of the audio current in the circuit 41 and consequently high frequency oscillations are impressed upon the antenna 24 modified by the human voice or other sounds.

A modified apparatus for generating and telephonically controlling high frequency oscillations is illustrated by Fig. 3. In this apparatus the high frequency oscillations are produced by the action of the coil 19 on the electron current and these oscillations are modulated by the electrostatic con trol member or grid 12. The winding 19 is connected by the conductors 50, 51 and 52 in series both with the secondary of the antenna transformer 53 and the secondary of a transformer 54, the primary winding of which is connected in circuit with the cathode 8 and the anode 17. Included in circuit with the secondary of the transformer 54 is an ,adjustable condenser 57. The primary winding of the transformer 54 is shunted by an adjustable condenser 58 and in series with this winding is a suitable source of direct current such as the battery 59. The cathode8 is maintained at incandescence by a heating battery 26 as in the case of the apparatus already described. By properly tuning the inductance and the capacity of the circuit 50, 51, 52 and the inductance and capacity of the circuit 55, 56, the current in the coil 19 oscillates bet-ween values which produces corresponding oscillations of the electron current.

The oscillations can be modified by an electric field in any desired manner. In the specific apparatus illustrated the oscillations are modulated by atelephone transmitter 60 which is connected in series with a battery 61 to the primary of a transformer 62, the secondary of which is connected by the conductors 63,64, respectively to the cathode 8 and the grid 12.

lVhat I claim as new and desire to secure by Letters Patent of the United States, 1s,-

1. The combination of a thermionic electric discharge device, means for'controlling the flow of current therein by the conjoint action of a variable electrostatic field and a variable electromagnetic field and means for varying said fields independently.

2. An electric device comprising means for generating an electron current, means for controlling said current by a magnetic field varying between a value sufiicient to reduce said current and a lesser value and means electrically independentof said first means for simultaneously subjecting said electron current to a variable electric field.

3. An electric device comprising an evacuated container, an electron emitting cathode therein,a co-operating anode, a grid located between said cathode and an anode,

an electromagnetic winding surrounding said container and means electrically independent of said grid for energizing said winding by a variable current.

4. An electric device comprising an evacuated container, a refractory cathode therein adapted to emit electrons when heated to incandesence, an anode arranged to circular symmetry about said cathode, an electrostatic control member for varying the electric field between said electrodes, independent means for producing a magnetic field substantially parallel to said cathode and means for varying at will said source of current connected to said elec-- receptacle containing a cathode adapted toemit electrons independently of gas ionization, an anode and an electrostatic control member, a source of current connected in circuit with said electrodes, a winding surrounding said receptacle, an oscillatory circuit connected to said winding, means for supplying said oscillatory circuit with energy from said electrode circuit and means for varying at will the electrostatic field of said control member.

7 The combination of an electron discharge apparatus containing a cathode adapted to emit electrons and an anode, a magnetic winding arranged to control a current between said electrodes, an oscillatory circuit connected to said winding, means for supplying said oscillatory circuit with current flowing between said electrodes, thereby producing electric oscillations, means'for radiating said oscillations, means for electrostatically controlling said oscillations and a telephone transmitter operatively connected to said electrostatic control means.

8. The method of controlling an electron discharge which consists in varying in a desired manner the electric field in the path of said discharge, and simultaneously subjecting said discharge to an electromagnetic field substantially at right angles to the path of said discharge and varying between a value at which the current carrying capacity of said device is materially reduced and a lesser value at which the current carrying capacity is substantially unaffected.

9. The method of controlling an electron discharge which consists in subjecting said discharge to an electromagnetic field substantially at right angles to the path of said discharge, varying said field in a regular manner -to produce oscillations in said electron current and modifying said oscillations in a desired manner by varying the electric field in the path of said discharge 10. The method of producing a variable electron discharge in a vacuous spacebetween an incandescent cathode and an anode which consists in impressing a substantially steady electric potential upon said electrodes to produce an electron discharge, super.- imposing upon the electric field of said discharge an electric field varying in a predetermined manner and conjointly subjecting said discharge to an electromagnetic field likewise subject to a predetermined variation, and so related to said discharge that an increase of field strength above a predetermined value materially reduces said discharge.

11. An electronic apparatus comprising the combination of means for producing an electron discharge, means for producing in the path thereof an electric field capable of varying'said discharge and electrically independent means for producing an electromagnetic field so oriented with respect to said discharge that at a suificient field value said discharge will be substantially suppressed.

12; A radio sending apparatus comprising an antenna, a source of energy, an electron discharge apparatus including an electrostatic control means, circuit connections between said apparatus and said antenna, means independent of said antenna circuit for electromagnetically controlling the operation of said electron discharge apparatus and means for varying at will the operation of one of said control means independently of the operation of the other means.

18. The combination of an electron discharge apparatus containing an electron emitting cathode and an anode, a source or" energy connected to said electrodes, means for generating an oscillating magnetic field adapted to cause an electron current between said electrodes to vary correspondingly and independent means for electrostatically controlling a discharge. between said electrodes.

14. The combination of an electron discharge apparatus comprising means for producing an electron discharge, means for generating a magnetic field varying between values at which said discharge is correspondingly varied in an inverse sense, means for generating an electrostatic field for modulating said discharge, and a work clrcuit connected to said apparatus for utilizing the variable current resulting from the combined effect of said magnetic and electromagnetic fields.

15. A sending apparatus for radio telephony comprising the combination of a work circuit, an electronic device having electrodes arranged in circular symmetry with respect to one another and provided with means for electrostatically controlling a discharge between said said electrodes, circuit connections between sald electrodes and said work circuit, a source of energy connected to feed power to said antenna through said electronic apparatus, a winding adapted to generate an electromagnetic field substantially parallel to the axis of said electrodes, means for supplying said Winding With variable current and a telephonic transmitter operatively connected'to the electrostatic control means of said electronic device.

In witness whereof, I have hereunto set my hand this 20th day of May, 1920.

ALBERT W. HULL. 

